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What are Castellation PCBs? Applications and Benefits 2023

Views: 533 Author: Site Editor Publish Time: 2023-05-29 Origin: Site

Printed circuit boards with castellated edges are designed with indentations or semi-plated holes on the edges. Castellated PCBs are often used in applications where space is limited, such as smartphones and other portable devices, because of these indentations that allow them to be soldered to another PCB or module. They provide a secure and reliable connection.

Castellated PCBs have the following advantages:

· Using them, two PCBs can be connected securely and reliably.

· Portable devices can benefit from their compactness and lightweight.

· The assembly process is faster and cheaper when they can be soldered easily.

The most important feature of the material used for the production of Castellation PCBs is good insulation - this allows you to avoid creating unwanted electrical connections between individual components.

 Most often, printed circuit boards are made of various types of laminates, for example, composite (CEM1, CEM3), phenol-paper (FR-2, FR-3), glass-epoxy (FR-4) or glass-Teflon (PTFE). A very important property of printed circuit boards is also the maximum operating temperature, which, depending on the material, can range from about 100°C to over 130°C. Substances limiting the risk of ignition are also added to each type of laminate.

Thickness and Stiffness

PCB boards vary in thickness and stiffness. There are thick plates (more than 1.5 mm in cross-section), thin plates (less than 0.5 mm), and foil-type plates (less than 0.2 mm). In addition, printed circuit boards can be single-, double- and multi-layer, which affect their properties and possible applications.

Current carrying capacity

Another important parameter is the maximum current load. It depends primarily on the thickness of the copper layer on the surface, from which the paths connecting electronic components are made. As a standard, Castellation PCBs are produced with a copper layer with a thickness of about 15 μm to over 100 μm.

The technology of assembly of electronic components

Printed circuit boards can be adapted to the assembly of components made in through-hole technology (THT, Through-Hole Technology) or surface technology (SMD, Surface-Mounted Devices). In the first case, the leads of electronic components are threaded through holes drilled in the board and soldered on the other side.

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On the other hand, in the surface technique, components are attached to the soldering pads located on the same side of the board.

How is Castellation PCB made?

Etching agents are used for the chemical treatment of the plates.

PCBs are made of larger sheets of insulating material that is machined to shape and thickness, then coated with copper. In the next stage, a map of paths to be found on the finished product is applied to the plate with special paint.

The Castellation boards are then chemically treated to remove the copper layer (outside the desired traces) and make electrical connections only on the intended traces - a process called etching. Finally, solder pads are prepared on the board for the assembly of electronic components and lamination is performed to avoid damage to the product during transport and operation.

Create your own PCB

PCBs are usually manufactured industrially on a large scale, but electronics engineers often also create single pieces designed for individual electronic projects - for this purpose, base plates, paints, and etchers are used in electronics stores. This solution allows you to adjust the parameters of printed circuit boards to the needs of specific projects because the layout of pins and paths can be planned in almost any configuration.

Various Castellation PCB applications

Castellation PCB boards are widely used in both industrial and hobby electronics. On a large scale, they are used, among others, as the basis for the creation of various modules in devices, for example in electronics and household appliances or small electronics, as well as in control systems for electrical systems of machines, installations, and vehicles.

 In contrast, individual pieces of individually designed and etched printed circuit boards are created by electronic engineers as part of projects, for example, robots or self-built electronic devices.

PCB boards are important components of electronic devices. Their high quality translates into a guarantee of the reliability of the equipment in which they will be installed. Because they play such an important role, manufacturers try to do everything to be sure of their proper operation.

For this purpose, they conduct several tests - some of them are standard elements of the contact electronics production process, and some are performed as additional services. What tests are we talking about?

Electrical testing of printed circuit boards

Castellation PCB production includes electrical testing of printed circuit boards. During this type of testing, it is checked whether there are any short circuits or breaks in the paths on the boards.

To assess this, the transition resistance between the test points and the leakage resistance between each trace and adjacent traces are measured. Such control allows to detection of possible errors and effectively eliminates them.

What is a flying probe test?

What is a flying probe? This is a testing method that involves the use of measuring probes moving in three axes. It allows you to detect possible errors in making connections on the PCB, including short circuits or breaks in the tracks.

 The optimal test software generation process works well for short-run production or prototype board testing. Modern flying probe testers also provide a relatively short duration, which allows them to be used for the entire production spectrum.

PCB Optical Testing (AOI)

The production of printed circuit boards also includes optical tests. Automated Optical Inspection, or AOI for short, allows you to assess assembly quality by visually inspecting the electronic components that have been soldered to the board.

With the help of 2D and 3D cameras moving over the printed circuit, photos of this circuit are taken and then compared with the reference images of elements from the library.

Optical testing allows you to detect both missing components and their incorrect placement, wrong elements, and soldering errors - even those that could not be noticed with the naked eye.

Ionic purity test

In addition, we test the ionic purity of the manufactured PCBs. Because the production of electronics to order at each stage is associated with the risk of creating impurities that may contribute to electromigration and thus cause damage to the finished device, we perform an ionic purity analysis.

The analysis is performed according to Ionic Analysis Methodologies using the Ionograph 500M device. We immerse the printed circuit in the tank with the solution, and then we examine the concentration of released ions in this solution.

On this basis, the algorithm calculates the degree of contamination of the surface, whether of the PCB itself or the PCB with assembled elements.

 The cleanliness of the surface of the electronics has a great influence on the reliability of the device especially in demanding applications, e.g. in high voltage circuits or in difficult environmental conditions: moisture, dust, large temperature changes, etc.

In-Circuit Test (ICT)

Our scope of testing does not end there. Surface mount SMT or through-hole THT can be evaluated against the actual values ​​of the assembled components. For this purpose, an ICT test (In Circuit Test) is performed to detect the presence or absence of electronic components, their incorrect assembly, wrong values, possible short circuits, interruptions and reverse polarity. ICT tests are classified as quick tests - the control lasts relatively short.

The measurement system consists of an adapter and gold-plated needles that contact the test points of the circuit. A great help is the placement of test points by the designer in the design of the board. It is possible to test virtually any plate with this method; however, the use of needles with less popular endings increases the cost of making the test matrix. Matrices of ICT testers are made for a specific PCB, therefore the ICT test is mainly used in medium and large series production.

Functional tests of Castellation PCBs

It is also possible to check whether the finished product works as intended. The PCB manufacturer conducts so-called functional tests (FCT), which verify the correct operation of the board. Measurement systems or dedicated testers supplied by the customer or prepared by contract electronics manufacturers on request and according to the customer's design are used for the tests.

 The tests may cover only the basic functions of the assembled circuit, which gives partial information about the correct functioning of the electronics

Why Victory PCB?

To sum up, quality control and the achievement of design assumptions is an investment that guarantees reliability and allows you to avoid many potential problems in the production of Castellation PCBs. Get a quick quote for Castellation PCB now.

About The Author

I am the Engineering and Sales supervisor working in Victorypcb from 2015. During the past years, I have been reponsible for all oversea exhibitions like USA(IPC Apex Expo), Europe(Munich Electronica) and Japan(Nepcon) etc. Our factory founded in 2005, now have 1521 clients all over the world and occupied very good reputation among them.

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